91Ó°ÊÓ

The speed at which a wave crest travels forward is represented as wave speed.In a time equal to one time period (T), a wave crest travels a distance of one wavelength\(\left( \lambda \right)\).

The time period of the wave is \(T = 3.0\,{\rm{s}}\).

The distance between two crests is equal to the wavelength of the wave. Thus, the wavelength of the wave is, \(\lambda = 7.0\;{\rm{m}}\).

The relation to find the speed of waves is given by,

\(\begin{aligned}{l}v &= \lambda \times f\\v &= \frac{\lambda }{T}\end{aligned}\)

Here, f is the frequency.

On substituting the given values in the above relation.

\(\begin{aligned}{c}v &= \frac{{7.0\;{\rm{m}}}}{{3.0\;{\rm{s}}}}\\ &= 2.3\;{\rm{m/s}}\end{aligned}\)

Thus, the speed of waves is 2.3 m/s.